linux-kernel - Re: [PATCH] MAINTAINERS: Add Helge as fbdev maintainer

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Date:   Mon, 24 Jan 2022 20:05:29 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Helge Deller <deller@....de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Sven Schnelle <svens@...ckframe.org>
Subject: Re: [PATCH] MAINTAINERS: Add Helge as fbdev maintainer

Hi

Am 24.01.22 um 19:38 schrieb Geert Uytterhoeven:
> Hi Daniel,
> 
> On Fri, Jan 21, 2022 at 9:55 AM Daniel Vetter <daniel@...ll.ch> wrote:
>> Just to clarify, since we had lots of smaller and bigger
>> misunderstandings in the thread thus far: DRM_FORMAT_RGB332 exists, so
>> drm support that already. The fbdev emulation doesn't yet, but all
>> that's needed for that is filling out the code to remap the drm
>> description to the fbdev format description for this case. Plus
>> testing it all works ofc with fbcon and whatelse. Note that RGB332  is
>> a bit more work than e.g. C4, since atm fbdev still uses only bpp to
>> identify formats, so would need to be switch over to drm_fourcc first
>> before adding anything which aliases with something existing (we have
>> C8 already wired up).
> 
> I doubt that RGB332 would be a bit more work than C4, as RGB332 is still
> 8 bpp, while C4 is less.  To support C4, all DRM code that cannot
> handle format->cpp[0] < 1 or drm_format_info_block_width() > 1 has to be
> fixed first.
> 
> On the plus side, I finally got my proof-of-concept Atari DRM driver
> working with fbcon on ARAnyM.  Mapping /dev/fb0 from userspace doesn't
> work (fbtest SEGVs while reading from the mapped frame buffer).  I don't
> know yet if this is a general issue without deferred I/O in v5.17-rc1,
> or a bug in the m68k MM code...
> 
> So far it supports C8 only, but I hope to tackle C4 and monochrome soon.
> Whether the end result will be usable on real hardware is still to be
> seen, but at least I hope to get some DRM code written...

That sounds pretty cool.

Best regards
Thomas

> 
> Gr{oetje,eeting}s,
> 
>                          Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                  -- Linus Torvalds

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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